Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q16795 (ubiquinone)
 5,455 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Co-enzyme Q10, or ubiquinone, is a nutrient that is produced in small amounts by the body and is also obtained from food. It plays a key role in helping the body convert food into energy. Co-enzyme Q10 is also an important antioxidant, the need for which appears to increase during HIV infection and in people who use certain lipid-lowering drugs called statins.
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PMID:Extra co-enzyme Q10 for statin-users? 1157 Feb 88

Reactive oxygen species (ROS) are known mediators of intracellular signaling cascades. Excessive production of ROS may, however, lead to oxidative stress, loss of cell function, and ultimately apoptosis or necrosis. A balance between oxidant and antioxidant intracellular systems is hence vital for cell function, regulation, and adaptation to diverse growth conditions. Thioredoxin reductase (TrxR) in conjunction with thioredoxin (Trx) is a ubiquitous oxidoreductase system with antioxidant and redox regulatory roles. In mammals, extracellular forms of Trx also have cytokine-like effects. Mammalian TrxR has a highly reactive active site selenocysteine residue resulting in a profound reductive capacity, reducing several substrates in addition to Trx. Due to the reactivity of TrxR, the enzyme is inhibited by many clinically used electrophilic compounds including nitrosoureas, aurothioglucose, platinum compounds, and retinoic acid derivatives. The properties of TrxR in combination with the functions of Trx position this system at the core of cellular thiol redox control and antioxidant defense. In this review, we focus on the reactions of the Trx system with ROS molecules and different cellular antioxidant enzymes. We summarize the TrxR-catalyzed regeneration of several antioxidant compounds, including ascorbic acid (vitamin C), selenium-containing substances, lipoic acid, and ubiquinone (Q10). We also discuss the general cellular effects of TrxR inhibition. Dinitrohalobenzenes constitute a unique class of immunostimulatory TrxR inhibitors and we consider the immunomodulatory effects of dinitrohalobenzene compounds in view of their reactions with the Trx system.
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PMID:Reactive oxygen species, antioxidants, and the mammalian thioredoxin system. 1172 1

Hypocholesterolemic preparations, inhibitors of the key enzyme of cholesterol biosynthesis beta-hydroxy-beta-methylglutaryl coenzyme A reductase (statins), block the synthesis of ubiquinone Q10, intermediate electron carrier in the mitochondrial respiratory chain. This should decrease energy supply to tissues. Daily peroral administration of beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitor simvastatin (24 mg/kg perorally) for 30 days had no effect on the contents of macroergic phosphates (ATP and creatine phosphate) in the liver, but decreased these parameters in the myocardium.
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PMID:Inhibitor of beta-hydroxy-beta-methylglutaryl coenzyme A reductase decreases energy supply to the myocardium in rats. 1178 91

Ubiquinone (coenzyme Q10), in addition to its function as an electron and proton carrier in mitochondrial electron transport coupled to ATP synthesis, acts in its reduced form (ubiquinol) as an antioxidant, inhibiting lipid peroxidation in biological membranes and protecting mitochondrial inner-membrane proteins and DNA against oxidative damage accompanying lipid peroxidation. Tissue ubiquinone levels are subject to regulation by physiological factors that are related to the oxidative activity of the organism: they increase under the influence of oxidative stress, e.g. physical exercise, cold adaptation, thyroid hormone treatment, and decrease during aging. In the present study, coenzyme Q homologues were separated and quantified in the brains of mice, rats, rabbits, and chickens using high-performance liquid chromatography. In addition, the coenzyme Q homologues were measured in cells such as NG-108, PC-12, rat fetal brain cells and human SHSY-5Y and monocytes. In general, Q1 content was the lowest among the coenzyme homologues quantified in the brain. Q9 was not detectable in the brains of chickens and rabbits, but was present in the brains of rats and mice. Q9 was also not detected in human cell lines SHSY-5Y and monocytes. Q10 was detected in the brains of mice, rats, rabbits, and chickens and in cell lines. Since both coenzyme Q and vitamin E are antioxidants, and coenzyme Q recycles vitamins E and C, vitamin E was also quantified in mice brain using HPLC-electrochemical detector (ECD). The quantity of vitamin E was lowest in the substantia nigra compared with the other brain regions. This finding is crucial in elucidating ubiquinone function in bioenergetics; in preventing free radical generation, lipid peroxidation, and apoptosis in the brain; and as a potential compound in treating various neurodegenerative disorders.
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PMID:Distribution of coenzyme Q homologues in brain. 1206 50

The purpose of this article is to summarise our studies, in which the main determinants and absorption of plasma coenzyme Q10 (Q10, ubiquinone) have been assessed, and the effects of moderate dose oral Q10 supplementation on plasma antioxidative capacity, lipoprotein oxidation resistance and on plasma lipid peroxidation investigated. All the supplementation trials carried out have been blinded and placebo-controlled clinical studies. Of the determinants of Q10, serum cholesterol, serum triglycerides, male gender, alcohol consumption and age were found to be associated positively with plasma Q10 concentration. A single dose of 30 mg of Q10, which is the maximum daily dose recommended by Q10 producers, had only a marginal elevating effect on plasma Q10 levels in non-Q10-deficient subjects. Following supplementation, a dose-dependent increase in plasma Q10 levels was observed up to a daily dose of 200 mg, which resulted in a 6.1-fold increase in plasma Q10 levels. However, simultaneous supplementation with vitamin E resulted in lower plasma Q10 levels. Of the lipid peroxidation measurements, Q10 supplementation did not increase LDL TRAP, plasma TRAP, VLDL+LDL oxidation resistance nor did it decrease LDL oxidation susceptibility ex vivo. Q10 with minor vitamin E dose neither decreased exercise-induced lipid peroxidation ex vivo nor muscular damage. Q10 supplementation might, however, decrease plasma lipid peroxidation in vivo, as assessed by the increased proportion of plasma ubiquinol (reduced form, Q10H2) of total Q10. High dose vitamin E supplementation decreased this proportion, which suggests in vivo regeneration of tocopheryl radicals by ubiquinol.
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PMID:Coenzyme Q10: absorption, antioxidative properties, determinants, and plasma levels. 1206 2

The efficacy and safety of ubiquinone (Q10) and nicotinamide were evaluated in a 6-month open-label trial in patients with the 3243A-->G mitochondrial DNA mutation. Blood lactate and pyruvate concentrations decreased, but there was little clinical improvement. Q10 and nicotinamide were well tolerated, but two patients died suddenly and unexpectedly during the trial. These deaths may have been unrelated to treatment. The unpredictable course of the disease makes evaluation of the clinical response difficult.
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PMID:Ubiquinone and nicotinamide treatment of patients with the 3243A-->G mtDNA mutation. 1239 67

The primary care physician is in a position to advise patients on the efficacy of alternative and complementary therapies as they relate to cardiovascular diseases. Anti-oxidant vitamin supplementation has not been shown to be efficacious in decreasing cardiovascular events. N-3 fatty acids appear to be beneficial in secondary prevention of cardiovascular events but their use in primary prevention is not clear. Adoption of vegetable-based diets, including whole grains, can be recommended to decrease cardiovascular events, lower cholesterol and help lower blood pressure. For patients with hypercholesterolemia, cholestin, a red-yeast rice supplement, has been shown to be effective. Garlic supplements may have some mild cholesterol-lowering effect, but this effect is not significant enough to recommend clinically. Herbal therapies with hawthorn and ubiquinone (Q10) are of possible benefit in congestive heart failure. An integrated program of rigorous diet, exercise and stress reduction in motivated patients with cardiovascular disease may have value as an alternative to cardiovascular medications and surgical interventions.
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PMID:Cardiovascular disease. 1239 14

The selenoprotein thioredoxin reductase (TrxR1) is an essential antioxidant enzyme known to reduce many compounds in addition to thioredoxin, its principle protein substrate. Here we found that TrxR1 reduced ubiquinone-10 and thereby regenerated the antioxidant ubiquinol-10 (Q10), which is important for protection against lipid and protein peroxidation. The reduction was time- and dose-dependent, with an apparent K(m) of 22 microm and a maximal rate of about 12 nmol of reduced Q10 per milligram of TrxR1 per minute. TrxR1 reduced ubiquinone maximally at a physiological pH of 7.5 at similar rates using either NADPH or NADH as cofactors. The reduction of Q10 by mammalian TrxR1 was selenium dependent as revealed by comparison with Escherichia coli TrxR or selenium-deprived mutant and truncated mammalian TrxR forms. In addition, the rate of reduction of ubiquinone was significantly higher in homogenates from human embryo kidney 293 cells stably overexpressing thioredoxin reductase and was induced along with increasing cytosolic TrxR activity after the addition of selenite to the culture medium. These data demonstrate that the selenoenzyme thioredoxin reductase is an important selenium-dependent ubiquinone reductase and can explain how selenium and ubiquinone, by a combined action, may protect the cell from oxidative damage.
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PMID:The mammalian cytosolic selenoenzyme thioredoxin reductase reduces ubiquinone. A novel mechanism for defense against oxidative stress. 1243 34

Inhibitors of the key enzyme of cholesterol biosynthesis beta-hydroxy-beta-methylglutaryl-coenzyme A reductase (statins) decrease cholesterol content in atherogenic low-density lipoproteins in patients with coronary heart disease and hypercholesterolemia, but inhibited biosynthesis of ubiquinone Q10 protecting low-density lipoproteins from free radical oxidation. Cerivastatin in a daily dose of 0.4 mg markedly increased the content of lipid peroxides in low-density lipoproteins. However, complex therapy with cerivastatin and antioxidant probucol (250 mg/day) was accompanied by a sharp decrease in the content of lipid peroxides in low-density lipoproteins in patients with coronary heart disease in vivo. These data indicate that antioxidant agents should be used in combination with inhibitors of beta-hydroxy-beta-methylglutaryl-coenzyme A reductase (hypolipidemic preparations) for the therapy of patients with coronary heart disease.
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PMID:Intensification of free radical oxidation of low-density lipoproteins in the plasma of patients with ischemic heart disease receiving beta-hydroxy-beta-methylglutaryl-coenzyme A reductase inhibitor cerivastatin and inhibition of low-density lipoprotein peroxidation with antioxidant probucol. 1245 65

This report describes an intervention study with healthy volunteers (20 smokers, 28 non-smokers) taking a food additive mainly containing vitamin C (ascorbic acid), vitamin E (alpha-tocopherol), ubiquinone (Q10), vitamin A and zinkoxide for four weeks in a double blind, randomized and placebo controlled manner. Before and after the intervention blood was withdrawn and general blood parameters were analyzed. In addition, lipid soluble antioxidants were analyzed in blood plasma by HPLC and the water soluble antioxidative properties were tested with the enzymic xanthin/xanthinoxidase-reaction. In summary the results show that the smoker-verum group exhibit a significant down regulation of the leukocyte counts. The test for antioxidants show the following significant differences after intervention: Smokers exhibit an increase of both vitamin E and coenzyme Q10 and an attenuation of their (before intervention) clearly increased water soluble-antioxidative potential, non-smokers showed only an increase of vitamin E and trends of an increase of Q10 and water soluble-antioxidative potential. These results may contribute to the discussion of the intrinsic deficiency brought about by smoking and the possible attenuation of part of these deficiency by increasing the intake of certain vitamins or food additives.
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PMID:Attenuation of blood parameters in smokers and non-smokers after intake of a complex food additive. 1262 38


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